The invention relates to a pen-caliper device that is especially useful to a physician (or other person) who must make frequent precise measurements on a graph and then make notations regarding the measurements.
A cardiologist frequently carries both a pair of dividers in a sheath and an ordinary ballpoint pen in his or her shirt pocket. When the cardiologist wishes to measure intervals or distances on an electrocardiogram (EKG), he or she removes the dividers from a sheath in which they are inserted to protect the cardiologist from the sharp end points of the pair of dividers. The pair of dividers is deployed to measure distances on the EKG. The sharp end points then are held against a numerical scale to obtain the desired numerical measurement. The cardiologist then removes the ballpoint pen from a pocket of his or her clothing and deploys it to make a corresponding entry on patient records or the like. Frequently, the sheath for the dividers is misplaced and lost. This prevents the cardiologist from putting the dividers in a pocket of his or her clothing because the sharp points poke through the cardiologist's clothing and skin.
U.S. Pat. No. 4,720,921 discloses a pair of dividers used as a navigational instrument, with a channel in the structure for frictionally receiving a writing instrument that can be gripped, removed from the channel, inverted, and reinserted with its writing tip protectively inside the channel. The disclosed navigational device includes various indicia that enable it to function as a protractor and as a distance measuring device. Although the navigational instrument incorporates a writing instrument and a pair of dividers or calipers, it would not be suitable for use by cardiologists, because the divider tips are unprotected by a sheath when not in use, and the writing tip cannot be protected except by removing the writing instrument, inverting it, and reinserting it in the receiving channel, which would be more inconvenient than the present practice of using a separate caliper and sheath and a conventional ballpoint pen. U.S. Pat. No. 4,388,759 discloses a relatively complex EKG caliper with various numerical scales. U.S. Pat. No. 1,564,908 discloses a pair of dividers with a bracket for holding a writing instrument the tip of which is adjacent to one of the sharp points of the pair of dividers. None of the foregoing devices can be used conveniently by a cardiologist without causing problems even more disconcerting than those described above for a conventional ballpoint pen and pair of dividers in a sheath.
It would be very desirable for cardiologists and others to have a single instrument for both measuring EKGs or the like and making notations, while avoiding the foregoing difficulties.